Vacuum separator

ABSTRACT

A vacuum separator of metal for separating impurities from halfrefined metal prepared by reducing a metal chloride by a metallic reducing agent. The impurities include the surplus or unreacted metallic reducing agent and reaction by-products. The vacuum separator comprises a body and a heating furnace. The body accommodates an inner cylindrical member with a carrier means carrying reduced half-refined metal to be treated. The body includes an upper portion holding the inner cylindrical member, and a lower portion receiving the surplus or unreacted reducing agent and the reaction by-products. The furnace includes a conduit connected to a vacuum pump to reduce the inner pressure of the body, a first portion heating the inner cylindrical member held by the upper portion of the body, and a second portion heating the lower portion of the body. The second portion of the furnace melts away crusts deposited in the vessel as solid substance firmly adhered to the wall of the lower portion of the body.

United States Patent Ishizuka 51 May 16, 1972 54 VACUUM SEPARATORPrimary Examiner-James M. Meister [72] Inventor: Hiroshi Ishizuka, 19-2Ebara, 6-chome, Attorney-waters Rodm Schwartz & Nlssen Shinagava-ku,Tokyo, Japan 57 1 ABSTRACT [22] Filed: Apr. 16, 1969 Appl. No.: 816,610

A vacuum separator of metal for separating impurities from half-refinedmetal prepared by reducing a metal chloride by a metallic reducingagent. The impurities include the surplus or unreacted metallic reducingagent and reaction by-products. The vacuum separator comprises a bodyand a heating furnace. The body accommodates an inner cylindrical memberwith a carrier means carrying reduced half-refined metal to be treated.The body includes an upper portion'holding the inner cylindrical member,and a lower portion receiving the surplus or unreacted reducing agentand the reaction by-products. The furnace includes a conduit connectedto a vacuum pump to reduce the inner pressure of the body, a firstportion heating the inner cylindrical member held by the upper portionof the body, and a second portion heating the lower portion of the body.The second portion of the furnace melts away crusts deposited in thevessel as solid substance firmly adhered to the wall of the lowerportion of the body.

5 Chins, 2 Drawing Figures 1:; j 1. ill.

PATENTEDMAY 16 I972 sum 1 or 2 FIG. 1

PRIOR ART PATENTEDMAY 16 m2 SHEET 2 [IF 2 FIG.2

VACUUM SEPARATOR This invention relates to a vacuum separator, and moreparticularly to a vacuum separator for refining metals.

Some metals, such as titanium and zirconium, have a high melting pointand are active at high temperatures, and accordingly, it is difficult torefine them. What is called the Kroll process has been used for refiningthose metals which are difficult to refine, in which a chloride of themetal is reduced by a metallic reducing agent, such as magnesium ofsodium. The reduced product obtained according to the Kroll process isspongy and contains impurities consisting of reaction by-productsincluding chlorides (e.g., magnesium chloride or sodium chloride) andreaction remainders, such as non-reacted raw material chlorides andunreacted reducing agent. In order to produce the desired pure metal inthe spongy form, the impurities must be completely eliminated from thereduced half-refined product, as far as possible.

In a known method of refining, the half-refined product obtainedaccording to the Kroll process (hereinafter referred to as simply as rawmaterial) is cut into chips, for instance, by a lathe and the chips arefurther refined through an acid treatment. A more popular refiningmethod is to use a vacuum separator adapted to hold a vessel for the rawmaterial, e.g., an inner cylindrical member, which is directly placed inthe vacuum separator for refining raw material by vacuum distillation.

A conventional device for such vacuum separation comprises an upperinner cylindrical member accommodating raw material to be refined; afurnace heating said upper inner cylindrical member; a lower innercylindrical member having a suction opening connected to a vacuum pump;a means for cooling the lower inner cylindrical member; and a vesseldisposed in said lower inner cylindrical member for receiving reactionby-products and reducing agent. The known device, however, has a numberof disadvantages. Namely, after separating impurities, the resultingrefined spongy metal products must be transferred to the next treatingstep either by raising the furnace and the body, or by lowering theinner cylindrical members of the device, and then crusts formed at thecooling means should be removed by crushing. The crusts are solidifieddeposits adhered to the surface of the cooling means and made ofby-products of the preceding refining process and the metallic reducingagent. In other words, the known device is operated in the so-calledbatch process, in which all the component elements of the device shouldbe reassembled for each refining operation. Moreover, the crushing ofthe crusts is done manually by using considerable time and man-power.The metallic reducing agent and the byproducts in the crusts are in theform of tightly adhered mixture, and thus they cannot be utilizeddirectly unless they are separated each other. Accordingly, the yield oftheir recovery is low.

Therefore, a principal object of the present invention is to provide avacuum separator of sturdy construction for refining those metals whichare difficult to refine, which overcomes and obviates the aforesaiddisadvantages of the conventional apparatus for the refining.

A specific object of the present invention is to provide a vacuumseparator for refining metals, in which a cooling portion itself canalso be heated for facilitating the melting of crusts deposited thereonso as to discharge the melted crust to the outside of the separator,thereby simplifying the conventional complicated process of crustremoval. With the vacuum separator according to the present invention,the refining process can be remarkably simplified and considerablesaving in man-power can be expected.

Another specific object of the present invention is to provide a vacuumseparator of the aforesaid construction, which facilitates theseparation of the melted crusts into the reaction byproducts and thereducing agent, whereby the recovery yield of the reducing agents isremarkably improved and, at the same time, the tedious process of theseparation of the crust components outside the vacuum separator can becompletely eliminated.

Other objects and a fuller understanding of the present invention may behad by referring to the following description to be taken in conjunctionwith the accompanying drawings, in which;

FIG. 1 is a vertical sectional view of a prior art or conventionalvacuum separator; and

FIG. 2 is a vertical sectional view of a vacuum separator according tothe present invention.

For refining metal with the conventional device in FIG. 1, the rawmaterial 18 is loaded in an upper inner cylindrical member 16, mountedwithin the body 10. The funnel-shaped member 26 and a lower innercylindrical member 20 are connected to inner cylindrical member 16, anda lid 28 leading to a vacuum spum (not shown) is airtightly fitted tothe body 10. The body 10 is thereafier evacuated by the vacuum pumpthrough the suction opening 30 to a pressure of about l0 mmI-Ig to 10mmI-Ig. The heating furnace 12 with heating coils 122 embedded in firebrick 121 surrounded by a housing 123 heats the thus evacuated body 10from the outside, so that the upper inner cylindrical member 16 isheated to about 1,000" C.

If magnesium is used as the reducing agent in the Kroll process, thesurplus or unreacted magnesium in the raw material 18 begins toevaporate at about 500 C and is completely evaporated at about 850 C. Atthe same time, the reduction by-product consisting of magnesium chloridebegins to evaporate at about 650 C and completely evaporated at about1,050 C. The vapor of magnesium and magnesium chloride evaporated fromthe raw material 18 is cooled and condensed in cooling jacket 14 andcollected in the vessel 22. A part of the vapor, however, solidifies andadheres to the inner surface of the lower inner cylindrical member 20and to the plates 24, and forms crusts. Upon completion of the refiningprocess by the heating separator, the body 10 is raised or the innermembers are lowered, so that the refined product in the upper innercylindrical member 16 can be removed for transferring to the nextprocess.

Then, the magnesium and the magnesium chloride'in the vessel 22 arerecovered, and the crusts deposited on the inner surface of the coolingjacket and the plates are manually crushed and scraped. Thus, therefining operation is completed.

The,crusts thus crushed and scraped contain the surplus or unreactedmetallic reducing agent and the chloride thereof in the state of firmlyadhered mixture. As a result, in order to separate the reducing agentand the by-product chloride for reuse, the crusts must be melted again.In other words, the crusts cannot be used directly.

The vacuum separator according to the present invention will now bedescribed in detail, referring to FIG. 2. As can be seen from FIG. 2,the upper portion of the separator of the invention is substantiallyidentical with that of the conventional separator as describedhereinbefore, with reference to FIG. 1. It should be noted, however,that a body 40 of the vacuum separator of the present invention consistsof an upper portion 42 and a lower portion 44, which can be completelyseparated one another at about the center of the body 40. An upperheating furnace 48 covered by iron housing 483 wherein a heating element482 is embedded in a fire-brick 481, heats an inner cylindrical member46 mounted in the upper portion 42 of the body, so that the raw material50 loaded in the inner cylindrical member 46 can be heated to evaporatethe surplus or unreacted reducing agent and the by-product chloridecontained in said raw material 50. The lower inner cylindrical member 44accommodates condensed and/or solidified reducing agents and theby-products, which are represented by 52 and 54 in FIG. 2. The vaporevaporated from the raw material 50 by the upper heating furnace 48 iscooled by gas forced into the vacuum separator by a blower connected toan inlet 91 provided between the upper portion 42 and the lower portion44 of the body. A part of the vapor condenses on the inner wall of thelower portion 44 of the body to form crusts 54, but a lower heatingfurnace 56 similar to that of the upper heating furnace and covered byiron housing 563 wherein a heating element 562 is embedded in afire-brick, heats and melts away such crusts 54.

The raw material 50 is loaded in the inner cylindrical member 46 havinga grate or a carrier 58 which is held by a support 60. A vacuum pump(not shown) is connected to a conduit 62 through a suitable connectingmeans 64, so that the inner pressure of the body 40 can be reduced. Theupper portion 42 and the lower portion 44 of the body 40 are separablyor detachably connected together with a packing 66 insertedtherebetween. The packing 66 is, for instance, made of heat-resistingrubber and provided with suitable protective cooling jackets 68 and 70.

With the vacuum separator of the aforesaid construction, according tothe present invention, the refining can be carried out substantially inthe same manner as that of the known separator, and the refined spongyproduct of the difficulty refinable metal can be removed from the upperinner cylindrical member 46 by raising only the upper heating furnaceand the upper portion 42 of the body. At the same time, the crusts 54are heated to about 800 C and melted by the lower heating furnace 56,and then collected in the lower portion 44 of the body. Furthermore, dueto the difference of the specific gravity, the reduc-ing agent andchloride as the reduction byproduct are collected in two separate moltenlayers at the bottom of the lower portion 44 of the body. Accordingly,the reducing agent and chloride can be separated by properly opening andclosing a valve or a cock 72 communicated with the lowest part of thebottom of the lower portion 44. The recovered reducing agent is storedor conveyed to the reducing process for reuse, while the chloride istransferred to an electrolytic process.

Furthermore, with the vacuum separator according to the presentinvention, the removal of the impurities from the lower portion of theseparator body does not affect the succeeding refining operation. Inother words, there is no need for removing the impurities, such ascrusts, deposited in the lower portion of the body at the end of eachrefiningoperation. In fact, according to the vacuum separator of thepresent invention, it is possible to repeat the refining process severaltimes without removing the impurities from the vacuum separator body, sothat the impurities collected during the preceding several refiningprocesses can be removed at one time after completion of the repeatedrefining processes.

Thus, the overall refining process is greatly simplified, andconsiderable saving is possible in man-power. With the collection of thereducing agent and by-product chloride in the form of separate moltenlayers, the recovery yield of the reducing agent and by-productchlorides is considerably improved, and the economy of the overallprocess is improved.

EXAMPLE:

3,330 Kg of the raw material which had been manufactured by reacting 760Kg of metallic magnesium with 2,600 Kg of zirconium tetrachloride in areduction furnace and by cooling the reaction products, and whichcomprises 1000 Kg of metal- The raw material was loaded within thisinner cylindrical member.

Grate or carrier 58 stainless steel disc member having a large number ofopennings each of which diameter is about mm.

Upper heating furnace 48 electrical heating type furnace of fire-bricksouter diameter 2200 mm. inner diameter 1300 mm. length 3000 mm.

Lower heating furnace 56 similar type to the upper heating furnace.

outer diameter 2200 mm. inner diameter 1800 mm. length are contained inthe raw material 50 as the impurities. Then,

lic zirconium, 230 Kg of unreacted metallic magnesium and 2,100 Kg ofmagnesium chloride, was refined with use of an apparatus as specified inthe followings.

Upper portion 42 of the body 40 iron cylindrical member the lowerportion 44 of the body 40 was cooled and, at the same time, the upperportion 42 thereof was heated for 24 hours at about 950 C, the innerpressure of the body 40 being reduced to l010 mm Hg by a pump throughthe conduit 62 so as to retain only about l,000 Kg of metallic zirconiumin the inner cylindrical member. The resulting sponge like shapedmetallic zirconium is quite pure and contains a smaller amount of oxygenthan that as separated with use of a conventional process and apparatusas illustrated in FIG. 1 and thus the yield thereof according to thepresent invention is improved at least about 5 percent as compared withthat of the conventional process.

After completion of the reaction, the upper heating furnace 48 and theupper portion 42 of the body 40 were raised to remove the innercylindrical member 46 accommodating the resulting refined metalliczirconium and to mount a fresh inner cylindrical member in which thefresh raw material has been charged.

The rearranged apparatus, in which the inner cylindrical memberaccommodates the fresh raw material, was operated in the manner asreferred to above.

After such refining operations were repeated several times, a step formelting and removing impurities including crusts was carried outtogether with the next refining step or as a separate step from saidrefining. The impurities removing step was carried out by heating thelower portion 44 of the body 40 with the use of the lower furnace atabout 800-850 C and by discharging melted impurities through the valve72.

In this case, the unreacted metallic magnesium was recovered at a rateof about 220 Kg/l batch which corresponds to percent or more, andmagnesium chloride was recovered at a rate of about 2,100 Kg/l batchwhich corresponds substantially to percent. This shows the excellentadvantages of the present device as compared with the following data asattained by the conventional device.

recovering rate about 70 7: about 80 metallic magnesium magnesiumchloride Iclaim:

l. A vacuum separator for separating unreacted reducing agent andreaction by-product from half-refined metal prepared by reducingchloride of a metal with a metallic reducing agent, said separatorcomprising an inner cylindrical member, including means for carrying thehalf-refined reduced metal to be refined; a body including a firstportion for accommodating said inner cylindrical member and a secondportion for accommodating the reducing agent and the by-productfractionally evaporated from the half-refined metal; heat resistingmeans interposed between said first and second portions forinterconnecting said latter portions to one another; conduit meansconnected to a vacuum pump for reducing the inner pressure of said body;and furnace means including a first portion for heating said innercylindrical member and a second portion for heating said second portionof the body; such that crusts deposited on the inside walls of saidsecond portion of the body are heated and melted by said second portionof said furnace means.

2. A vacuum separator according to claim 1 wherein said heat resistingmeans comprises a packing and protective cooling means interposedbetween said first and second portions of the body, such that said firstportion can be separated from said second portion for loading said innercylindrical member with the half-refined metal and for removal ofrefined metal.

3. A vacuum separator according to claim 1 and further comprising acooling gas inlet provided between said first and said second portionsof said body, said cooling gas inlet being connected to an outsideblower for feeding cooling gas to condense said fractionally evaporatedimpurities.

4. A vacuum separator according to claim 1 and further comprising aconduit means communicating with the bottom of said lower portion of thebody and having a valve means mounted on said conduit means, wherebysaid molten reducing agent and reaction by-product, including saidmolten crusts, are led to the outside of the separator while separatingthe reducing agent from the reaction by-product by utilizing thedifierence of specific gravities therebetween.

5. A vacuum separator according to claim 1, wherein said body iscompletely surrounded by said furnace means.

2. A vacuum separator according to claim 1 wherein said heat resistingmeans comprises a packing and protective cooling means interposedbetween said first and second portions of the body, such that said firstportion can be separated from said second portion for loading said innercylindrical member with the half-refined metal and for removal ofrefined metal.
 3. A vacuum separator according to claim 1 and furthercomprising a cooling gas inlet provided between said first and saidsecond portions of said body, said cooling gas inlet being connected toan outside blower for feeding cooling gas to condense said fractionallyevaporated impurities.
 4. A vacuum separator according to claim 1 andfurther comprising a conduit means communicating with the bottom of saidlower portion of the body and having a valve means mounted on saidconduit means, whereby said molten reducing agent and reactionby-product, including said molten crusts, are led to the outside of theseparator while separating the reducing agent from the reactionby-product by utilizing the difference of specific gravitiestherebetween.
 5. A vacuum separator according to claim 1, wherein saidbody is completely surrounded by said furnace means.